DESCRIPTION¶
The nsenter command executes program in the
namespace(s) that are specified in the command-line options (described
below). If program is not given, then "${SHELL}" is run
(default: /bin/sh).
Enterable namespaces are:
mount namespace
Mounting and unmounting filesystems will not affect the
rest of the system, except for filesystems which are explicitly marked as
shared (with mount --make-shared; see /proc/self/mountinfo for
the shared flag). For further details, see mount_namespaces(7)
and the discussion of the CLONE_NEWNS flag in clone(2).
UTS namespace
Setting hostname or domainname will not affect the rest
of the system. For further details, see uts_namespaces(7).
IPC namespace
The process will have an independent namespace for POSIX
message queues as well as System V message queues, semaphore sets and shared
memory segments. For further details, see ipc_namespaces(7).
network namespace
The process will have independent IPv4 and IPv6 stacks,
IP routing tables, firewall rules, the /proc/net and
/sys/class/net directory trees, sockets, etc. For further details, see
network_namespaces(7).
PID namespace
Children will have a set of PID to process mappings
separate from the nsenter process. nsenter will fork by default
if changing the PID namespace, so that the new program and its children share
the same PID namespace and are visible to each other. If --no-fork is
used, the new program will be exec’ed without forking. For further
details, see pid_namespaces(7).
user namespace
The process will have a distinct set of UIDs, GIDs and
capabilities. For further details, see user_namespaces(7).
cgroup namespace
The process will have a virtualized view of
/proc/self/cgroup, and new cgroup mounts will be rooted at the
namespace cgroup root. For further details, see
cgroup_namespaces(7).
time namespace
The process can have a distinct view of
CLOCK_MONOTONIC and/or CLOCK_BOOTTIME which can be changed using
/proc/self/timens_offsets. For further details, see
time_namespaces(7).
If you want to create a new namespace, use unshare(1). Once
created, you can run a program in it using nsenter.
OPTIONS¶
Various of the options below that relate to namespaces take an
optional file argument. This should be one of the
/proc/[pid]/ns/* files described in namespaces(7), or the
pathname of a bind mount that was created on one of those files.
-a, --all
Enter all namespaces of the target process by the default
/proc/<pid>/ns/* namespace paths. The default paths to the target
process namespaces may be overridden by namespace-specific options (e.g.,
--all --mount=path).
The user namespace will be ignored if it is the same as the
caller’s current user namespace. It prevents a caller that has
dropped capabilities from regaining those capabilities via a call to
setns(2). See the man page for more details.
-t, --target PID[:inode]
Specify a target process to get contexts from. The paths
to the contexts specified by
PID are:
/proc/pid/ns/mnt
the mount namespace
/proc/pid/ns/uts
the UTS namespace
/proc/pid/ns/ipc
the IPC namespace
/proc/pid/ns/net
the network namespace
/proc/pid/ns/pid
the PID namespace
/proc/pid/ns/user
the user namespace
/proc/pid/ns/cgroup
the cgroup namespace
/proc/pid/ns/time
the time namespace
/proc/pid/root
the root directory
/proc/pid/cwd
the working directory respectively
Optionally, a process can be addressed with the format
PID:inode. The inode identifies the unique process’s
file descriptor. To retrieve a process’s inode number you can use the
getino(1) utility.
-m,
--mount[=<file|:nsid>]
Enter the mount namespace. If no argument is specified,
enter the mount namespace of the target process. If file or
:nsid is specified, enter the mount namespace specified by file
or nsid.
-u,
--uts[=<file|:nsid>]
Enter the UTS namespace. If no argument is specified,
enter the UTS namespace of the target process. If file or :nsid
is specified, enter the UTS namespace specified by file or
nsid.
-i,
--ipc[=<file|:nsid>]
Enter the IPC namespace. If no argument is specified,
enter the IPC namespace of the target process. If file or :nsid
is specified, enter the IPC namespace specified by file or
nsid.
-n,
--net[=<file|:nsid>]
Enter the network namespace. If no argument is specified,
enter the network namespace of the target process. If file or
:nsid is specified, enter the network namespace specified by
file or nsid.
-N, --net-socket fd
Enter the network namespace of the target
process’s socket. It requires --target process specified.
Supported since Linux 5.6.
-p,
--pid[=<file|:nsid>]
Enter the PID namespace. If no argument is specified,
enter the PID namespace of the target process. If file or :nsid
is specified, enter the PID namespace specified by file or
nsid.
-U,
--user[=<file|:nsid>]
Enter the user namespace. If no argument is specified,
enter the user namespace of the target process. If file or :nsid
is specified, enter the user namespace specified by file or
nsid. See also the --setuid and --setgid options.
--user-parent
Enter the parent user namespace. Parent user namespace
will be acquired from any other enabled namespace. If combined with
--user option the parent user namespace will be fetched from the user
namespace and replace it.
-C,
--cgroup[=<file|:nsid>]
Enter the cgroup namespace. If no argument is specified,
enter the cgroup namespace of the target process. If file or
:nsid is specified, enter the cgroup namespace specified by file
or nsid.
-T,
--time[=<file|:nsid>]
Enter the time namespace. If no argument is specified,
enter the time namespace of the target process. If file or :nsid
is specified, enter the time namespace specified by file or
nsid.
-G, --setgid gid
Set the group ID which will be used in the entered
namespace and drop supplementary groups. nsenter always sets GID for
user namespaces, the default is 0. If the argument "follow" is
specified the GID of the target process is used.
-S, --setuid uid
Set the user ID which will be used in the entered
namespace. nsenter always sets UID for user namespaces, the default is
0. If the argument "follow" is specified the UID of the target
process is used.
--keep-caps
When the --user option is given, ensure that
capabilities granted in the user namespace are preserved in the child
process.
--preserve-credentials
Don’t modify UID and GID when entering the user
namespace. The default is to drop supplementary groups and set GID and UID to
0.
-r, --root[=directory]
Set the root directory. If no directory is specified, set
the root directory to the root directory of the target process. If directory
is specified, set the root directory to the specified directory. The specified
directory is opened before switching to the requested namespaces.
-w, --wd[=directory]
Set the working directory. If no directory is specified,
set the working directory to the working directory of the target process. If
directory is specified, set the working directory to the specified directory.
The specified directory is opened before switching to the requested
namespaces, which means the specified directory works as a "tunnel"
to the current namespace. See also --wdns.
-W, --wdns[=directory]
Set the working directory. The directory is opened
after switching to the requested namespaces and after calling
chroot(2). The options --wd and --wdns are mutually
exclusive.
-e, --env
Pass environment variables from the target process to the
new process being created. If this option is not provided, the environment
variables will remain the same as in the current namespace.
-F, --no-fork
Do not fork before exec’ing the specified program.
By default, when entering a PID namespace, nsenter calls fork
before calling exec so that any children will also be in the newly
entered PID namespace.
-Z, --follow-context
Set the SELinux security context used for executing a new
process according to the already running process specified by --target
PID. (The util-linux has to be compiled with SELinux support otherwise the
option is unavailable.)
-c, --join-cgroup
Add the initiated process to the cgroup of the target
process.
-h, --help
Display help text and exit.
-V, --version
Display version and exit.
